In golf, leading "wire to wire" means being in the lead at the end of every round/day of the tournament, after all play has been completed for that round/day. So a golfer who "led wire-to-wire" may actually have been trailing other golfers for several holes in the middle of a round.

This makes the use of "wire to wire" in golf slightly different than it is in other sports. For instance, if the Blue Jays win their division "wire-to-wire" in 2010 (yeah, right), that means that they would have been in first place on every single day of the season, starting with the first game. (Of course, in baseball, leaderboards/standings are not "live" but are only tallied after games are finished.)

The term "wire to wire" (as well as "down to the wire" and "under the wire") comes from horse racing, where in the days before cameras a wire would be strung over the finish line of the track to help officials determine a winner in a close race. Another wire was strung across the starting gate to check for false starts. If a horse led from "wire to wire," it led from start (first wire) to finish (second wire).

Sources: Golf Channel, IOL, World Wide Words